This Phase II, open-label, parallel-arm study will evaluate the safety, tolerability, pharmacokinetics and antiviral activity of ritonavir-boosted danoprevir in combination with Pegasys (peginterferon alfa-2a) and Copegus (ribavirin) in treatment-naïve patients of Asian origin with chronic hepatitis C genotype 1. Patients will receive danoprevir 125 mg plus ritonavir 100 mg as fixed dose tablet orally twice daily in combination with weekly Pegasys 180 mcg subcutaneously and Copegus 1000-1200 mg orally daily in divided doses. Treatment duration is 12 weeks in patients without cirrhosis and 24 weeks in patients with compensated cirrhosis.